Use HSTS in apache conf. Fixes #47.
Remove includeSubDomains option from HSTS header.
Moved Apache configuration to Plinth setup script.

James added the Apache Headers module to the makefile, but not the
FreedomBox-Setup configuration script.  However, it's ridiculous to
have multiple locations for that same logic, so now the makefile uses
the setup script for the Apache configuration instead.

Also, the modules are now fancy and alphabetized.